Hal Schenck
Hal Schenck
Mathematics Department
Auburn University
Auburn, AL 36849
tel: 334-844-4290
fax: 334-844-6555
hks0015@auburn.edu
Who am I?
I am a Professor and Rosemary Kopel Brown Eminent Scholars Chair in the
Mathematics Department at
Auburn University . My research interests are interdisciplinary: my background is in commutative algebra and algebraic geometry. I'm especially interested in problems which can be studied from a computational standpoint, and in interactions with problems in applied mathematics. My current applied work is on two themes:
Approximation theory, Interpolation, and Geometric modeling
Topological data analysis and trading networks
On the more theoretical side, I enjoy working on problems at the
interface of discrete geometry and algebra; for example
Hyperplane and hypersurface arrangements
Gorenstein rings, Artinian algebras, Lefschetz properties
Toric varieties
I've also worked on questions involving free resolutions and syzygies, coding theory, rational surfaces and postulation, stability and jump loci of vector bundles, and geometric complexity theory. I did my graduate work at Cornell , and postdoctoral work at Cornell ,
Harvard , and
Northeastern . Prior to coming
to Auburn I served as Chair
at Iowa State , and I've also been a professor at Illinois and Texas A&M . Here's my vita html and pdf .
Information for students
In Spring 2022 I taught sections 2660-85
and 2660-95 of
Linear Algebra. Past classes I've taught at Auburn include Abstract Algebra
II , Calculus
III , Computational
Algebra , and Topological
Data Analysis . For a cool application of linear algebra, here is a link to a minicourse I taught for talented high school students
on the mathematics of Google .
For students interested in commutative algebra and algebraic geometry,
here are a few thoughts on what to read and how to choose an advisor. Below are webpages of students and postdocs:
Sean Grate (Auburn, current)
Joanie Morris (Auburn, current)
Beihui Yuan
(Ph.D. Cornell 2021, joint with M. Stillman)
Matt Mastroeni (Ph.D. Illinois 2018)
Eliana Duarte (Ph.D. Illinois 2017)
Nathan Fieldsteel
(Ph.D. Illinois 2017)
Michael DiPasquale
(Ph.D. Illinois 2015)
Jimmy Shan
(Ph.D. Illinois 2014)
Alexandra
Seceleanu (Ph.D. Illinois 2011)
Jimmy Kimball
(Ph.D. Texas A&M 2008)
Stefan
Tohaneanu (Ph.D. Texas A&M 2007)
Terry
McDonald (Ph.D. Texas A&M 2006)
Amy
Huang (Assistant Research Professor, current)
Jayan Mukherjee
(ICERM Bridge Postdoc, 2021-2022)
Mucyo Karemera (Postdoc,
2021-2022, joint with R. Molinari)
Bill
Trok (Postdoc, 2020-2021, joint with L. Oeding)
Javid Validashti (Postdoc, 2011-2014)
Leah
Gold (NSF-VIGRE Postdoc, 2002-2005)
Here are notes from a lunch talk I've given
several times on the Job Hunt .
Books
Toric Varieties
(American Mathematical Society, 2011). This book (with
David Cox and
John Little ) covers standard and advanced topics in toric geometry. In the first part we begin each chapter with a section on basic algebraic geometry background. Advanced topics include equivariant cohomology, Hirzebruch-Riemann-Roch, and the toric minimal model program.
Computational Algebraic Geometry (Cambridge, 2003). This book grew out of an
undergraduate algebraic geometry class (Math 99 ) I taught at Harvard, and covers basics of commutative algebra and Grobner bases. It also gives a quick taste of homological algebra (Ext and Tor) and a bit of sheaf cohomology.
Upcoming/Recent talks and conferences
Fields
Institute Semester: Commutative Algebra and Applications, Toronto, Canada (2025)
Fields
Institute Workshop: Lefschetz Properties, Toronto, Canada (2023)
ICERM workshop:
Algebraic Geometry in Spectral Theory, Brown University (2023)
CIRM
conference: Written Geometry: Commutative Algebra, Luminy, France (2023)
INdAM conference: The Strong and Weak Lefschetz Properties, Cortona, Italy (2022)
INdAM
conference: Approximation Theory and Numerical Analysis, Cortona, Italy (2022)
Arrangements in
Ticino, Switzerland (2022)
BIRS-CMO
Workshop on Algebraic Methods in Coding Theory,
Oaxaca (2022)
MFO Workshop
on Toric Geometry, Oberwolfach (2022)
MFO Mini-Workshop on Interpolation, Approximation, and Algebra, Oberwolfach (2022)
Applied Algebra and Geometry, Swansea (2021)
Algebraic
Geometry (Alex Dimca Retirement), Ischia (2021)
SIAM conference on Applied Algebraic Geometry, (2021)
Chern
Institute, Symposium on Physics and Geometry, Nankai (2021)
Lorentz
Center: Metrics
in Multiparameter Persistence, Leiden (2021)
Università
Roma (Tor Vergata) workshop on algebra of multivariate splines, Rome (2021)
MFO Workshop on Logarithmic vector fields and freeness of divisors, Oberwolfach (2021)
IPM
Workshop on Commutative Algebra, Tehran (2021)
CIMAT School on Geometric and Topological Data Analysis, Guanajuato, Mexico (2020)
CIMPA School on Syzygies, Joao Pessoa, Brazil (2019)
CIRM workshop on Lefschetz properties in algebra, geometry, combinatorics, Luminy (2019)
MFO workshop on toric geometry, Oberwolfach (2019)
MSRI-NCTS Toric varieties in Taipei (summer graduate school), (2019)
Ideals, Varieties, Applications, Amherst (2019)
ICERM Nonlinear Algebra in Applications, Brown University (2018)
Algebraic representations in computer aided geometric design, Barcelona (2018)
BIRS-CMO Multiparameter Persistent Homology, Oaxaca (2018)
BIRS New Trends in Syzygies, Banff (2018)
CBMS Applications of polynomial systems, TCU (2018)
MFO Topology of Arrangements and Representation Stability, Oberwolfach (2018)
ICERM Geometry and Topology of Data, Brown University (2017)
Hausdorff Institute, Applied and computational algebraic topology, Bonn (2017)
Mittag-Leffler Institute, Lefschetz properties in algebra, geometry, combinatorics, Stockholm (2017)
Centro De Georgi, Combinatorics, geometry, topology and applications, Pisa, (2017)
BIRS-CMO, Ordinary and symbolic powers of ideals, Oaxaca, (2017)
Sante Fe Institute, Working group on geometric complexity theory (2016)
Oxford, Industrial and Applied Mathematics Seminar (2016)
KIAS conference on Syzygies, exterior algebra, and coherent sheaf cohomology, Jeju, Korea, (2016)
BIRS-CMO Computational algebra and surface modeling, Oaxaca, (2016)
Mathematical Methods for Curves and Surfaces, Tonsberg, Norway (2016)
INdAM Homological and computational methods in commutative algebra, Cortona (2016)
MFO Toric geometry, Oberwolfach (2016)
BIRS Lefschetz Properties and Artinian Algebras, Banff (2016)
MFO Arrangements of subvarieties and applications, Oberwolfach (2016)
ICERM Computational topology in arrangement theory, Brown University (2015) (stream talk)
Geometry and Data Analysis, University of Chicago (2015)
ICMS conference on Minimal free resolutions, Betti numbers, and combinatorics, Edinburgh (2015)
Oxford, Geometry and Analysis Seminar (2015)
MFO workshop on approximation theory and algebraic geometry, Oberwolfach (2015)
FoCM Computational algebraic geometry, Montevideo (2014)
INdAM conference on Configuration Spaces, Cortona (2014)
BIRS Hyperplane Arrangements, Wonderful Compactifications, and Tropicalization, Banff (2014)
Southwest Local Algebra Meeting, Texas A&M (2014)
RIMS conference on Characteristic classes and hyperplane arrangements, Kyoto (2013)
KUMUNU conference on
Commutative algebra and algebraic geometry, Missouri (2013)
SIAM algebraic geometry meeting (2013) and toric tutorial (2013)
NSF-DFG Graduate/Postdoc summer school: Syzygies in Berlin (2013)
BIRS Algebraic Geometry and Geometric Modeling, Banff (2013) (stream talk)
MSRI year on commutative algebra, (2012-13)
AMS sectional meeting invited address, New Orleans (2012)
MFO Cohomology rings and fundamental groups of arrangements, Oberwolfach (2012)
BIRS Syzygies in Algebraic Geometry, Banff (2012)
MFO Toric Geometry, Oberwolfach (2012)
PIMS conference: Arrangements and applications, Vancouver (2011)
INdAM-MSRI-SMI workshop on toric varieties, Cortona (2011)
BIRS Topological methods in toric geometry, symplectic geometry, and combinatorics, Banff (2010)
MFO Linear series on algebraic varieties, Oberwolfach (2010)
Configuration spaces: geometry, combinatorics, topology, Centro De Giorgi, Pisa (2010)
AMS special session on Combinatorial algebra, Lexington (2010)
AMS special session on Zonotopal algebra, San Francisco (2010)
Mathematical Society of Japan seasonal institute, Hokkaido (2009)
AIM Combinatorial challenges in toric varieties (2009)
2nd workshop on Algebraic Geometry and Approximation Theory (2009)
Bluegrass Algebra conference (2009)
Fields Institute Conference in honor of Peter Orlik (2008)
Macaulay2 Conference, Cornell (2008)
MFO Surface modelling and syzygies, Oberwolfach (2007)
MFO Toric varieties and projective normality, Oberwolfach (2007)
Conference and Workshop Organization
Fields
Institute Semester: Commutative Algebra and Applications, Toronto, Canada (2025)
INdAM conference: Approximation Theory and Numerical Analysis, Cortona, Italy (2022)
MFO Mini-Workshop on Interpolation, Approximation, and Algebra, Oberwolfach (2022)
SIAM conference on Applied Algebraic Geometry, (2021)
MFO workshop on toric geometry, Oberwolfach (2019)
MSRI-NCTS Toric varieties in Taipei (summer graduate school), (2019)
Ideals, Varieties, Applications, Amherst (2019)
Berkeley conference on Free resolutions and computational algebra, (2017)
BIRS-CMO workshop on computational algebra and surface modeling, Oaxaca, (2016)
MFO workshop on toric geometry, Oberwolfach (2016)
ICERM workshop on Computational geometric topology in arrangement theory, Brown University (2015)
MFO workshop on approximation theory and algebraic geometry, Oberwolfach (2015)
AMS special session on toric varieties (2014)
Macaulay2 Research Meeting and School (2014)
IMSE symposium on Applied Geometry, Topology and Networks (2014)
SIAM tutorial on toric varieties: math in the mountains (2013)
NSF-DFG Graduate/Postdoc summer school: Syzygies in Berlin (2013)
AMS special session on approximation theory and geometric modelling, New Orleans (2012)
Illinois-Purdue Algebra Geometry and Combinatorics Day 4/28/2012
Commutative Algebra and Algebraic Geometry Conference - UIUC (2011)
PIMS conference: Arrangements and applications-Vancouver (2011)
INdAM-MSRI-SMI workshop on toric varieties, Cortona (2011)
MSRI Graduate workshop on toric varieties (2009)
AMS-MRC Workshop on Computational Algebra & Convexity, Snowbird (2008)
MFO workshop on Surface modelling and syzygies, Oberwolfach (2007)
Publications
Calabi-Yau threefolds in
P^n and Gorenstein rings (with Mike
Stillman and Beihui Yuan ),
Advances in Theoretical and Mathematical Physics , to appear.
Nets in P^2 and Alexander Duality (with
Nancy
Abdallah ),
Discrete and
Computational Geometry , to appear.
Algebraic properties of Hermitian sums of squares (with Jennifer Brooks and Dusty
Grundmeier ),
Proceedings of the A.M.S. ,
150, (2022), 3471-3476.
Schemes supported on the
singular locus of a hyperplane arrangement in P^n (with Juan Migliore and Uwe Nagel ), International Mathematics
Research Notices , 1, (2022), 140-170.
The simplest minimal free resolutions in P^1 x P^1 ,
(with Nicolas Botbol and
Alicia Dickenstein ), in Commutative Algebra , Springer Verlag (2021), 113-145.
The Hessian polynomial and
the Jacobian ideal of a reduced hypersurface in P^n , (with Laurent
Buse , Alexandru
Dimca , and Gabriel Sticlaru),
Advances
in Mathematics , 392, (2021), 22 pages.
Quadratic Gorenstein rings
and the Koszul property I (with Matt Mastroeni and Mike Stillman ),
Transactions of the A.M.S. ,
374, (2021), 1077-1093.
Quadratic Gorenstein rings and the Koszul property II , (with Matt Mastroeni and Mike Stillman ), International Mathematics
Research Notices , to appear.
Rees Algebras, Syzygies, and Geometric Modeling, in Applications of polynomial systems , by David Cox , CBMS Regional Conference Series in Mathematics 134 , (2020), 121-135.
The Weak Lefschetz property for quotients by Quadratic Monomials (with Juan Migliore and Uwe Nagel ), Mathematica Scandinavica , 126,
(2020), 41-61.
Trading
Networks and Hodge Theory (with Richard Sowers and Rui Song ), Journal of
Physics Communications , (2020), 21pp.
A new bound for smooth
spline spaces (with Mike
Stillman and Beihui
Yuan ), Journal
of Combinatorial Algebra , 4, (2020), 359-367.
Stratifying
multiparameter persistent homology (with Heather Harrington , Nina Otter
and Ulrike
Tillmann ), SIAM Journal on
Applied Algebra and Geometry , 3, (2019), 439-471.
Logarithmic vector fields for curve configurations in P^2 with quasihomogeneous singularities , (with Hiroaki Terao and Masahiko Yoshinaga ), Mathematical Research Letters , 25, (2018), 1977-1992.
The method of shifted partial derivatives cannot separate the permanent from the determinant (with Klim Efremenko , J.M. Landsberg , Jerzy Weyman ), Mathematics of Computation , 87, (2018), 2037-2045.
On minimal free
resolutions of subpermanents and other ideals arising in complexity
theory (with Klim Efremenko ,
J.M. Landsberg , Jerzy Weyman ), Journal
of Algebra , 503, (2018), 8-20.
Subdivision and spline
spaces (with Tatyana Sorokina ),
Constructive
Approximation , 47, (2018), 237-247.
Codes from surfaces with small Picard number ,
(with
John Little ), SIAM
Journal on Applied Algebra and Geometry , 2, (2018), 242-258.
Polynomial interpolation in higher dimension: from simplicial complexes to GC sets (with Nathan Fieldsteel ), SIAM Journal on Numerical Analysis , 55 (2017), 131-143.
Algebraic methods in Approximation theory , Computer Aided Geometric Design , 45 (2016), 14-31.
Tensor product surfaces and linear syzygies (with Eliana Duarte ), Proceedings of the A.M.S. , 144 (2016), 65-72.
Chen ranks and resonance , (with
Dan Cohen ), Advances in Mathematics , 285 (2015), 1-27.
Finitely many smooth d-polytopes with n lattice points , (with
Bogart , Haase , Hering , Lorenz , Nill , Paffenholz , Rote , Santos ), Israel Journal of Mathematics , 207, (2015), 301-330.
Geometry of Wachspress surfaces , (with Corey Irving ), Algebra & Number Theory , 8 (2014), 369-396.
Splines on the Alfeld split of a simplex and type A root systems , Journal of Approximation Theory , 182 (2014), 1-6.
Syzygies and singularities of tensor product surfaces of bidgree (2,1) , (with Alexandra Seceleanu and Javid Validashti ), Mathematics of Computation , 83 (2014), 1337-1372.
Local cohomology of logarithmic forms , (with Graham Denham , Matthias Schulze , Max Wakefield , Uli Walther ), Annales de l'Institut Fourier , 63 (2013), 1177-1203.
Commutative algebra of subspace and hyperplane arrangements , (with Jessica Sidman ), in Commutative Algebra , Springer Verlag (2013), 639-665.
Toric Hirzebruch-Riemann-Roch via
Ishida's theorem on the Todd genus , Proceedings of the A.M.S. , 141 (2013), 1215-1217.
High rank linear syzygies on low rank quadrics , (with
Mike Stillman ), American Journal of Mathematics , 134 (2012), 561-579.
Equivariant Chow cohomology of nonsimplicial toric varieties , in Transactions of the A.M.S. , 364 (2012) 4041-4051.
Hyperplane Arrangements: Computations and Conjectures , in Advanced Studies in Pure Mathematics , 62, (2012) 323-358.
Recent developments and open problems in linear series , (with the MFO miniworkshop crew ), Contributions to Algebraic Geometry (P. Pragacz, ed.) EMS publishing (2012) 93-140.
Resonance varieties via blowups of P^2 and scrolls , in International Mathematics Research Notices , 20, (2011) 4756-4778.
Inverse systems, Gelfand-Tsetlin patterns and the weak Lefschetz property , (with Brian Harbourne , Alexandra Seceleanu ), in Journal of the London Mathematical Society , 84, (2011) 712-730.
Euler characteristic of coherent sheaves on simplicial torics via the Stanley-Reisner ring , in Journal of Mathematical Physics , 51, (2010) doi 112304.
The weak Lefschetz property and powers of linear forms in K[x,y,z] ,
(with
Alexandra Seceleanu ), in Proceedings of the A.M.S. , 138 (2010) 2335-2339.
Freeness of Conic-Line arrangements in P^2 ,
(with
Stefan Tohaneanu ), in Commentarii
Mathematici Helvetici , 84 (2009) 235-258.
Holonomy Lie algebras and the LCS formula for
subarrangements of A_n ,
(with
Paulo Lima-Filho ), International Mathematics Research Notices , 8 (2009) 1421-1432.
Piecewise polynomials on polyhedral complexes , (with
Terry Mcdonald ), Advances in Applied Mathematics , 42 (2009), 82-93.
The Orlik-Terao algebra and 2-formality ,
(with
Stefan Tohaneanu ), Mathematical Research Letters , 16 (2009), 171-182.
Efficient computation of resonance varieties via Grassmannians ,
(with
Paulo Lima-Filho ), Journal of Pure and Applied Algebra , 213 (2009), 1606-1611.
A case study in bigraded commutative algebra ,
(with
David Cox and
Alicia Dickenstein ), in "Syzygies and Hilbert Functions", edited
by
Irena Peeva , Lecture notes in Pure and Applied Mathematics 254 ,
(2007), 67--112.
Betti numbers and
degree bounds for some linked zero schemes ,
(with
Leah Gold and
Hema Srinivasan ),
Journal of Pure and Applied Algebra , 210, (2007), 481-491.
Syzygies, multigraded regularity and toric varieties ,
(with
Milena Hering and
Gregory G. Smith ), Compositio Mathematica , 142, (2006), 1499-1506.
Resonance, linear syzygies, Chen groups, and the Bernstein-Gelfand-Gelfand correspondence ,
(with
Alex Suciu ), in Transactions of the A.M.S. , 358, (2006), 2269-2289.
Toric surface codes and
Minkowski sums ,
(with
John Little ), SIAM
Journal on Discrete Mathematics , 20, (2006), 999-1014.
Derivation modules of orthogonal duals of hyperplane arrangements ,
(with
Joseph P.S. Kung ), in Journal of Algebraic Combinatorics , 24, (2006), 253-262.
Cayley-Bacharach and
evaluation codes on complete intersections ,
(with
Leah Gold and
John Little ), in Journal of
Pure and Applied Algebra , 196, (2005) p. 91-99.
Linear systems on a
special rational surface , in Mathematical Research Letters , 11, (2004) p. 697-714.
Lattice polygons and
Green's theorem , in Proceedings of the A.M.S. , 132, (2004) p. 3509-3512.
Elementary modifications and line configurations in P^2 ,
in Commentarii
Mathematici Helvetici , 78, (2003) p. 447-462.
Local complete intersections in P^2 and Koszul syzygies ,
(with
David Cox ), in Proceedings of the A.M.S. , 131, (2003) p. 2007-2014.
Lower central series and free resolutions of hyperplane arrangements ,
(with
Alex Suciu ), in Transactions of the A.M.S. , 354, (2002) p. 3409-3433.
Cohomology vanishing and a problem in approximation theory ,
(with
Peter Stiller ), in Manuscripta Mathematica , 107,
(2002) p. 43-58.
The module of logarithmic p-forms of a locally free arrangement ,
(with Mircea Mustata ), in Journal of Algebra , 241,
(2001) p. 699-719.
On a conjecture of Rose ,
(with John Dalbec ), in
Journal of Pure and Applied Algebra , 165, (2001) p. 151-154.
A
rank two vector bundle associated to a three arrangement, and its
Chern polynomial , in Advances in Mathematics , 149,
(2000) p. 214-229.
Subalgebras
of the Stanley-Reisner ring , in Discrete and Computational Geometry , 21, (1999) p. 551-556.
Fat points, inverse systems, and piecewise polynomial functions ,
(with
Anthony Geramita ), in Journal of Algebra , 204,
(1998) p. 116-128.
A spectral sequence for splines , in Advances in Applied
Mathematics , 19, (1997) p. 183-199.
Local cohomology of bivariate splines ,
(with
Mike Stillman ), in Journal of Pure and Applied Algebra , 117-118, (1997) p. 535-548.
A family of ideals of minimal regularity and the Hilbert series of C^r(\Delta ),
(with
Mike Stillman ), in Advances in Applied
Mathematics , 19, (1997) p. 169-182.
Preprints
Free resolutions and Lefschetz properties of some Artin Gorenstein rings of codimension four (with
Nancy
Abdallah ).
Quaternary quartic forms and Gorenstein rings (with
Grzegorz
Kapustka ,
Michal
Kapustka , Kristian Ranestad , Mike
Stillman and Beihui Yuan ).
Computational mathematics
Macaulay2: A program for computing in commutative algebra and
algebraic geometry.
CoCoA: Another option for computing in commutative algebra and
algebraic geometry.
Porta (and others): Programs for
polyhedral geometry.
Singular: A program for computations
in local rings and singularities.
Schubert: A program for enumerative
geometry.
Splinetool:
Macaulay2 script which builds the chain complexes and allows computation of
various homology modules
associated to splines.
Arrangetool:
Macaulay2 script for computations involving three arrangements.
MPH:
Macaulay2 scripts for computations involving multiparameter persistent
homology.
Useful math sites
Association for Mathematical Research
American Math Society
Society for Industrial and Applied Math
Algebraic
Geometry preprints
MSRI (Berkeley).